Barcodes have been utilized for identifying and pricing objects for more than thirty years. Most typically, barcodes are used in retail to identify the item of merchandise. For example, a gallon of milk may contain a barcode that, when scanned, will notify the cashier of the price of the milk.
Yet in recent years, barcodes have acquired new purposes as computers and barcode scanners have become more portable. The circuitry required to scan a conventional one-dimensional barcode can now be housed in a device as small as a typical keychain. As a result, many mobile telephones, personal digital assistants (“PDAs”), and pagers can be retrofitted with or connected to a laser-based scanning device. This allows the mobile device to function as a scanner capable of storing hundreds or thousands of scanned barcodes.
Mobile devices with attached scanners have allowed for the development of a new niche in the wireless electronics business. Some companies have developed software and hardware which allows a user to scan any barcode and be redirected to media information (e.g., a website, product description, price, etc.) about the scanned product. These programs provide a link between the physical and online world which previously did not exist.
However, mobile devices with attached scanners possess some drawbacks which have curtailed their expansion into the mobile marketplace. First, there are few mobile devices produced for the general public that contain integrated laser-based scanners. Therefore, for a user to acquire scanning capability for a mobile device, he/she must purchase additional equipment. The additional scanning equipment also adds size and weight to the mobile device, thereby reducing its mobility.
Currently, many cell phones and mobile devices are available with built-in cameras. The explosion of the availability of affordable digital cameras and their inclusion into mobile devices is driven by several factors. One of the most important is the recent availability of inexpensive image sensors based on CMOS technology. The cameras on these devices provide a means for capturing the barcode information which was previously only accessible via a laser-based scanner. Decoding barcode images from digital cameras included in mobile devices presents several difficult problems. These problems go well beyond the challenges addressed in commercial barcode readers.
Therefore, there clearly exists a need for a visual code system which is capable of being decoded on a camera-equipped mobile device. The visual code system should be able to be decoded from a wide range of angles and distances for use in different applications.